WASHINGTON - The White House's claim that e-mails sent on a Republican Party account might have been lost was challenged Thursday by Senate Judiciary Committee Chairman Patrick Leahy, who quipped that even his teenage neighbor could find them.

"They say they have not been preserved. I don't believe that!" Leahy shouted from the Senate floor as the dispute over the firing of federal prosecutors continued at a high pitch.

"You can't erase e-mails, not today. They've gone through too many servers," said Leahy, D-Vt. "Those e-mails are there; they just don't want to produce them. We'll subpoena them if necessary."

Later, Leahy and his committee's ranking Republican, Arlen Specter of Pennsylvania, said the White House and lawmakers should agree on an independent forensic expert to try to recover the messages.

White House officials insisted the administration was making a genuine effort to recover any missing e-mails that had been sent on an account sponsored by the Republican National Committee.

"I understand his point, but he's wrong," spokeswoman Dana Perino said of Leahy.

"We're being very honest and forthcoming," she added. "I hope that he would understand the spirit in which we have come forward and tried to explain how we screwed up our policy and how we're working to fix it."

With five days left before Attorney General Alberto Gonzales testifies before Leahy's committee in an effort to save his job, lawmakers kept up the pressure in the latest dispute to grow out of the Justice Department's firings of eight federal prosecutors.

In a letter to White House Counsel Fred Fielding, Leahy and Specter asked that the White House appoint "a fair and objective process for investigating this matter, including the use of a mutually trusted computer forensic expert."

In the meantime, behind closed doors, Judiciary Committee aides from both chambers continued their interviews with Justice Department officials.

The investigation has revealed that White House e-mails about official business - on electronic accounts intended for political matters - may be gone, in violation of a law that requires their preservation. Twenty-two White House officials, including political adviser Karl Rove, have the accounts sponsored by the Republican National Committee, administration officials say.

White House spokesman Scott Stanzel on Thursday could not rule out that some of the missing e-mails involved the attorney firings.

For the second day in a row, White House officials would not say whether the missing e-mails could be recovered. Leahy scoffed. "I've got a teenage kid in my neighborhood that can go get â€˜em for them," he told reporters. Retorted Perino: "I don't know if Senator Leahy is also an IT expert." White House officials could not say how many e-mails may have been lost. Meetings Thursday between lawmakers' aides and lawyers for the White House and RNC shed little new light, according to letters sent to the Gonzales and the RNC by the chairmen of congressional committees. Rep. Henry Waxman, chairman of the House Oversight and Government Reform Committee, said RNC lawyer Rob Kelner reported that roughly 50 White House officials have had e-mail accounts on the GOP committee's servers during Bush's tenure but the RNC may be able to recover only those sent from 2004 on. That's when the RNC put a hold on an automatic purge policy. It was unclear, Waxman wrote, whether the RNC had or would be able to recover e-mails written by White House officials, including Rove, and sent on the committee's account. A second Democratic House chairman, the Judiciary Committee's John Conyers of Michigan, asked RNC Chairman Robert M. Duncan in a separate letter to provide all e-mails from any government employee regarding the firings directly to his panel rather than to the White House first. "We would consider that to be an unjustified delay in responding to our request and potentially as an obstruction of our investigation," Conyers wrote. Conyers' request could set the RNC against the White House, which has offered to issue documents sought by the committee under certain conditions. Within hours of Conyers' letter to the RNC, the White House's Fielding responded by offering some RNC e-mails - but only as part of an agreement for documents and testimony that lawmakers have already rejected. Conyers' response was curt. "The Judiciary Committee intends to obtain the relevant e-mails directly from the RNC," he said in a statement. "The White House position seems to be that executive privilege not only applies in the Oval Office, but to the RNC as well." For its part, the RNC did not immediately return a call seeking comment. The Justice Department, meanwhile, prepared to release more documents detailing the decisions leading up to the firings of the eight prosecutors. The department has already given more than 3,400 pages of e-mails, schedules, memos and other documents to congressional panels. On Capitol Hill, Democrats tried to stave off charges of setting perjury traps for witnesses. Sen. Charles Schumer, D-N.Y., released 10 questions the panel would be asking Gonzales. "'I don't know' will not be an adequate response to any question by the committee," said Schumer, who is leading the investigation. Gonzales, who in the past has issued conflicting accounts of his role in the firings, emerged Thursday from weeks of closed-door preparations for his testimony to attend the funeral of an FBI agent in Readington Township, N.J. Also Thursday, the Senate Judiciary Committee authorized Leahy to issue subpoenas that would require the administration to surrender hundreds more documents and force two officials - Principal Associate Deputy Attorney General William Moschella and White House political aide Scott Jennings - to reveal their roles in the firings. The panel delayed for a week a vote on whether to authorize a subpoena for Rove's deputy, Sara Taylor.